A104425 Numbers n such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 5-less.

1, 4, 6, 7, 9, 10, 11, 18, 19, 23, 27, 29, 30, 32, 40, 41, 42, 43, 44, 49, 60, 61, 63, 67, 69, 70, 73, 74, 79, 80, 110, 111, 131, 140, 143, 144, 166, 170, 171, 179, 180, 181, 183, 184, 187, 189, 193, 196, 199, 200, 201, 202, 206, 209, 223, 228, 229, 233, 261, 263, 270

Offset: 1

Author

Zak Seidov, Mar 07 2005

Keywords

• nonn
• base

Comments

From the first 3000 primes, only 369 are such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 5-less.

Crossrefs

Cf. A104419-A104428.

Programs

Mathematica

id[x_]:=IntegerDigits[x];pr[i_]:=Prime[i];ra=Range[3000];A104425=Select[ra, Position[Union[id[ # ], id[pr[ # ]], id[pr[ # ]+# ], id[pr[ # ]-# ], id[pr[ # ]*# ]], 5]=={}&]
flQ[n_]:=Module[{pr=Prime[n]},Union[DigitCount[{n,pr,pr+n,pr-n,pr*n},10,5]] == {0}]; Select[Range[300],flQ] (* Harvey P. Dale, May 29 2014 *)